The invention relates to a measuring arrangement for the electrically uncoupled function testing of operating systems which comprise a current-carrying conductor.
For the electrically uncoupled function testing of operating loudspeakers, a measuring arrangement is known (DE-German Book: H. Sahm, xe2x80x9cHiFi Loudspeakersxe2x80x9d, 3rd Edition, Franzis Publishers, Mxc3xcnchen, 1985, Chapter 29: xe2x80x9cLoudspeaker Measurementsxe2x80x9d), in the case of which the oscillation coil pertaining to the loudspeaker forms a current-carrying conductor, to which a microphone is assigned as the sensor, which, as an electromechanical transducer, senses the oscillations caused by the oscillation coil as signals which, by way of an amplifier, are fed to an analysis unit, such as a frequency analyzer, a level recorder or the like.
In addition, a system is known (German Patent Document DE 4308796 C2) for monitoring and diagnosing mechanical systems, thus, for example, for a damage diagnosis in the case of machines, such as the roller bearing diagnosis, in the case of which the oscillations caused by mechanical defects, such as bearing irregularities or bearing damages, are sensed and processed. The starting points are always oscillations triggered by mechanical situations which oscillations are detected and evaluated by analyzing the envelope curve. Periodic signals are therefore analyzed.
For the potential-free monitoring of the ignition systems of internal-combustion engines, capacitively or inductively operating measuring systems are also known from practice. These systems operate current-proportionally (inductive primary detectors) or voltage-proportionally (capacitive primary detectors), and phase shifts exist in the case of the current-proportionally operating inductive as well as in the case of the voltage-proportionally operating capacitive primary detectors. In addition, capacitive primary detectors (high pass) do not detect low frequencies and inductive primary detectors (low pass) do not detect high frequencies so that the achievable results also do not supply any information on the effective output.
It is an object of the invention to monitor and diagnose systems comprising current-carrying conductors, specifically including the detection of one-time, periodic or non-periodic events and the obtaining of one-time periodic or non-periodic control quantities or automatic control quantities for the respective system as such or for the system and the arrangement, machine or device pertaining thereto.
This object is achieved by providing a measuring arrangement for the electrically uncoupled function testing of operating systems which comprise a current-carrying conductor and in the case of which an electromechanical transducer is assigned to the conductor in a direct mechanical coupling by way of a substantially incompressible medium, which transducer detects oscillations caused by the conductor, and the detected oscillations being supplied to at least one analyzing unit by way of an amplifier.
By means of the invention, for systems as such, which comprise an electric conductor as well as for arrangements, machines and/or devices equipped with such systems and/or interacting with such systems, an electrically uncoupled and thus galvanically separate detection of signals for a monitoring, a diagnosis, a control and an automatic control is permitted, in the case of which the signal detection takes place effective-output-proportionally and without phase shift over the whole frequency range, that is, also for very high frequencies. By way of the electromechanical transducer, the oscillations of the electric conductor are detected in this case in a potential-free manner over the whole operating range, the obtained signals being proportional to the energy course in the electric conductor. Since the correlation is identical with respect to the time and phase and proportional with respect to the amplitude, the mechanical energy course detected by way of the oscillations is also comparable to the electric energy course in the electric conductor. The detection of the energy course allows an evaluation of the system and conclusions on its primary as well as secondary functions. In addition, the measuring arrangement according to the invention permits comparisons between several conductors of a system among one another so that whole systems can be monitored, and this can take place with respect to constructional characteristics, such as bondings and connection devices as well as with respect to their functional sequences.
Because of these characteristics, but particularly also because of its immunity to interferences and its simplicity, the measuring arrangement according to the invention is suitable particularly for a use in motor vehicles, and here particularly for the use in connection with internal combustion engines,; thus, mainly for the electrically uncoupled function testing of an operating ignition coil of an ignition system; in the sense of the invention, the electric conductor being formed by the ignition coil, for evaluating the ignition system as a whole as well as its primary and secondary ignition functions. By comparisons of the ignition coils of the ignition system, the system as a whole can be monitored, and the ignition coils, the bondings and the connection devices as well as the spark plugs can be evaluated in their functionality, specifically in an interaction with the combustion. Thus, ignition failures can be detected in order to possibly switch off the fuel injection and prevent damage to the catalyst.
Although the use of the measuring arrangement in conjunction with ignition systems of internal-combustion engines represents a preferred use in connection with motor vehicles, within the scope of the invention, particularly also in combination with the use of the measuring arrangement with respect to ignition systems of internal-combustion engines, additional vehicle-related applications may be particularly expedient. Thus, the measuring arrangement according to the invention is suitable for applications in connection with electrically controlled and/or operated injection valves, particularly electromagnetically operated injection valves, such as pump - nozzle elements or injectors of common rail injection systems. Corresponding applications exist within the scope of the invention also for electromagnetic valve timing gears or electrically operated or electrically controlled actuators used for different purposes. In addition, the measuring arrangement according to the invention can be used in connection with relays, deflection systems, such as tubes or elementary particle accelerators, electric motors, generators, dynamos and/or transformers, which have electric conductors, for example, in the form of coils, so that, particularly in connection with vehicles in which electric operating and adjusting devices are increasingly used, measuring arrangements can be applied which operate according to the same principle.
Within the scope of the invention, strain gauges, piezoresistive transducers or piezoceramic transducers may preferably be used as electromechanical transducers.
A particularly expedient further development of the electromechanical transducer is represented by a piezoceramic element constructed as a knock sensor, as available as a tested structural member and already used particularly also in automobile construction in industrial scale manufacturing, and thus available at reasonable cost. Relative to the above-addressed application of the measuring arrangement in connection with ignition coils, the electromechanical transducer can be arranged, for example, as the further development as the knock sensor, externally with respect to the ignition coil or may be combined as a structural element with the ignition coil or may be integrated into the latter. The direct mechanical coupling can be implemented in a simple manner by way of a medium which essentially cannot be compressed, thus preferably an at least almost rigid coupling.
Since the measuring arrangement according to the invention relative to the described preferred use in connection with ignition systems of internal-combustion engines is independent of the type of the used ignition technique, the integration of the electromechanical transducer in the form of a knock sensor into the ignition coils also offers the best premises for applying, as the result of the signal analysis in the engine timing unit, the proportionality factor required for the ignition or combustion voltage in the engine timing unit. When energy-controlled ignition systems are used which, as the result of the special analysis of the ion current, supply information on knocking, combustion pressure and/or also combustion failures, the measuring arrangement also offers the possibility of producing in a potential-free manner, a reference to the ion current and, as a result, testing and analyzing the combustion quality, whereby additional information becomes available for controlling and/or automatically controlling the internal-combustion engine.
An embodiment, which in this context supplies particularly expedient and extensive information, in connection with internal-combustion engines of motor vehicles consists of assigning to the ignition unit, in an assignment to the ignition coil, an electromechanical transducer in the form of a knock sensor and additionally mechanically coupling it also with the spark plug so that, by way of the knock sensor, the sound signals of the ignition coil can be detected in a potential-free manner over the whole ignition range, specifically proportionally to the energy course in the ignition coil, as well as the sound pressure signals of the combustion. Such a combined usage is economically particularly advantageous and, in addition, permits conclusions on the mechanical condition of the internal-combustion engine as a whole while directly detecting the combustion sequences, so that combustion failures as well as early ignitions (knocking) can be immediately detected and corresponding control measures, for example, switching off the fuel injection for protecting the catalyst or adjusting the ignition in the late direction, can be initiated.
The example of an ignition unit with the ignition coil and the spark plug illustrates in a generalizing manner that the electromechanical transducer as the vibration transducer can definitely be arranged in different positions; thus, for example, between the ignition coil and the spark plug, in the ignition coil or, relative to the ignition coil, opposite the spark plug.
In the following, the invention will be explained in detail by means of embodiments, in which the measuring arrangement is illustrated as an example in its use in ignition systems of internal-combustion engines.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.